从文件中读取 - 错误的文件类型？

Question

我无法从简单的文本文件中读取,似乎无法弄清楚原因.我以前做过这个,我不确定问题是什么.任何帮助,将不胜感激!

import java.io.File;
import java.util.Scanner;

public class CS2110TokenReader {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        File theFile = new File("data1.txt");
        Scanner scnFile = new Scanner(theFile);

        try {
            scnFile = new Scanner(theFile);
        } catch (Exception e) {
            System.exit(1);
        }
        while (theFile.hasNext()) {
            String s1 = theFile.next();
            Double d1 = theFile.nextDouble();

            System.out.println(s1 + "   " + d1);
        }

    }

}

---

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
    The method hasNext() is undefined for the type File
    The method next() is undefined for the type File
    The method nextDouble() is undefined for the type File

    at CS2110TokenReader.main(CS2110TokenReader.java:20)

---

它甚至不会扫描下一行.这是我的目标.扫描和阅读.

Answer 1

while (theFile.hasNext()) {  // change to `scnFile.hasNext()`
    String s1 = theFile.next();  // change to `scnFile.next()`
    Double d1 = theFile.nextDouble();  // change to `scnFile.nextDouble()`

    System.out.println(s1 + "   " + d1);
}

您正在引用Scanner类的方法File.更换theFile用scnFile在所有的调用.

其次,要调用next()和nextDouble(),但只检查hasNext()一次.这可能会让你NoSuchElementException在某个时间点.在你真正阅读它之前,确保你有一个阅读的输入.